// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
 * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
 *
 * Fixed rate clock implementation
 */

#include <linux/clk-provider.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/err.h>
#include <linux/of.h>
#include <linux/platform_device.h>

/*
 * DOC: basic fixed-rate clock that cannot gate
 *
 * Traits of this clock:
 * prepare - clk_(un)prepare only ensures parents are prepared
 * enable - clk_enable only ensures parents are enabled
 * rate - rate is always a fixed value.  No clk_set_rate support
 * parent - fixed parent.  No clk_set_parent support
 */

#define to_clk_fixed_rate(_hw) container_of(_hw, struct clk_fixed_rate, hw)

static unsigned long clk_fixed_rate_recalc_rate(struct clk_hw *hw,
                unsigned long parent_rate)
{
        return to_clk_fixed_rate(hw)->fixed_rate;
}

static unsigned long clk_fixed_rate_recalc_accuracy(struct clk_hw *hw,
                unsigned long parent_accuracy)
{
        struct clk_fixed_rate *fixed = to_clk_fixed_rate(hw);

        if (fixed->flags & CLK_FIXED_RATE_PARENT_ACCURACY)
                return parent_accuracy;

        return fixed->fixed_accuracy;
}

const struct clk_ops clk_fixed_rate_ops = {
        .recalc_rate = clk_fixed_rate_recalc_rate,
        .recalc_accuracy = clk_fixed_rate_recalc_accuracy,
};
EXPORT_SYMBOL_GPL(clk_fixed_rate_ops);

struct clk_hw *__clk_hw_register_fixed_rate(struct device *dev,
                struct device_node *np, const char *name,
                const char *parent_name, const struct clk_hw *parent_hw,
                const struct clk_parent_data *parent_data, unsigned long flags,
                unsigned long fixed_rate, unsigned long fixed_accuracy,
                unsigned long clk_fixed_flags)
{
        struct clk_fixed_rate *fixed;
        struct clk_hw *hw;
        struct clk_init_data init = {};
        int ret = -EINVAL;

        /* allocate fixed-rate clock */
        fixed = kzalloc(sizeof(*fixed), GFP_KERNEL);
        if (!fixed)
                return ERR_PTR(-ENOMEM);

        init.name = name;
        init.ops = &clk_fixed_rate_ops;
        init.flags = flags;
        init.parent_names = parent_name ? &parent_name : NULL;
        init.parent_hws = parent_hw ? &parent_hw : NULL;
        init.parent_data = parent_data;
        if (parent_name || parent_hw || parent_data)
                init.num_parents = 1;
        else
                init.num_parents = 0;

        /* struct clk_fixed_rate assignments */
        fixed->flags = clk_fixed_flags;
        fixed->fixed_rate = fixed_rate;
        fixed->fixed_accuracy = fixed_accuracy;
        fixed->hw.init = &init;

        /* register the clock */
        hw = &fixed->hw;
        if (dev || !np)
                ret = clk_hw_register(dev, hw);
        else if (np)
                ret = of_clk_hw_register(np, hw);
        if (ret) {
                kfree(fixed);
                hw = ERR_PTR(ret);
        }

        return hw;
}
EXPORT_SYMBOL_GPL(__clk_hw_register_fixed_rate);

struct clk *clk_register_fixed_rate(struct device *dev, const char *name,
                const char *parent_name, unsigned long flags,
                unsigned long fixed_rate)
{
        struct clk_hw *hw;

        hw = clk_hw_register_fixed_rate_with_accuracy(dev, name, parent_name,
                                                      flags, fixed_rate, 0);
        if (IS_ERR(hw))
                return ERR_CAST(hw);
        return hw->clk;
}
EXPORT_SYMBOL_GPL(clk_register_fixed_rate);

void clk_unregister_fixed_rate(struct clk *clk)
{
        struct clk_hw *hw;

        hw = __clk_get_hw(clk);
        if (!hw)
                return;

        clk_unregister(clk);
        kfree(to_clk_fixed_rate(hw));
}
EXPORT_SYMBOL_GPL(clk_unregister_fixed_rate);

void clk_hw_unregister_fixed_rate(struct clk_hw *hw)
{
        struct clk_fixed_rate *fixed;

        fixed = to_clk_fixed_rate(hw);

        clk_hw_unregister(hw);
        kfree(fixed);
}
EXPORT_SYMBOL_GPL(clk_hw_unregister_fixed_rate);

#ifdef CONFIG_OF
static struct clk_hw *_of_fixed_clk_setup(struct device_node *node)
{
        struct clk_hw *hw;
        const char *clk_name = node->name;
        u32 rate;
        u32 accuracy = 0;
        int ret;

        if (of_property_read_u32(node, "clock-frequency", &rate))
                return ERR_PTR(-EIO);

        of_property_read_u32(node, "clock-accuracy", &accuracy);

        of_property_read_string(node, "clock-output-names", &clk_name);

        hw = clk_hw_register_fixed_rate_with_accuracy(NULL, clk_name, NULL,
                                                    0, rate, accuracy);
        if (IS_ERR(hw))
                return hw;

        ret = of_clk_add_hw_provider(node, of_clk_hw_simple_get, hw);
        if (ret) {
                clk_hw_unregister_fixed_rate(hw);
                return ERR_PTR(ret);
        }

        return hw;
}

/**
 * of_fixed_clk_setup() - Setup function for simple fixed rate clock
 * @node:       device node for the clock
 */
void __init of_fixed_clk_setup(struct device_node *node)
{
        _of_fixed_clk_setup(node);
}
CLK_OF_DECLARE(fixed_clk, "fixed-clock", of_fixed_clk_setup);

static int of_fixed_clk_remove(struct platform_device *pdev)
{
        struct clk_hw *hw = platform_get_drvdata(pdev);

        of_clk_del_provider(pdev->dev.of_node);
        clk_hw_unregister_fixed_rate(hw);

        return 0;
}

static int of_fixed_clk_probe(struct platform_device *pdev)
{
        struct clk_hw *hw;

        /*
         * This function is not executed when of_fixed_clk_setup
         * succeeded.
         */
        hw = _of_fixed_clk_setup(pdev->dev.of_node);
        if (IS_ERR(hw))
                return PTR_ERR(hw);

        platform_set_drvdata(pdev, hw);

        return 0;
}

static const struct of_device_id of_fixed_clk_ids[] = {
        { .compatible = "fixed-clock" },
        { }
};

static struct platform_driver of_fixed_clk_driver = {
        .driver = {
                .name = "of_fixed_clk",
                .of_match_table = of_fixed_clk_ids,
        },
        .probe = of_fixed_clk_probe,
        .remove = of_fixed_clk_remove,
};
builtin_platform_driver(of_fixed_clk_driver);
#endif